JP4119782B2 - Focus control device for optical information storage device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a focus control device for an optical information storage device, and more particularly to a focus control device for an optical information storage device that performs focusing by swinging a lens with respect to a storage medium.
[0002]
In a recording or reproducing apparatus for an optical information storage disk such as a compact disk (CD), a versatile disk (DVD), or a magneto-optical disk (MO, MD), a laser beam is condensed on the disk by an objective lens and reflected light thereof. It is a mechanism for reading playback information and servo information.
[0003]
In such an apparatus, focus servo control is performed so that the focal point of the laser beam is always connected to the recording film surface of the disc against the shake of the optical information storage disc caused by the rotation. In the focus servo control, the objective lens is controlled so as to keep the distance between the objective lens and the disk constant by feeding back a focus error signal obtained from the reflected light of the disk.
[0004]
In recent years, as the recording density is increased or the information recording / reproducing transfer speed is increased, the distance (gap) between the disc and the objective lens or the magnetic field modulation coil tends to be close, and the value is several tens of μm or less. There is also. When focus servo is applied to such a narrow gap, it is very difficult to arrange a stopper for the objective lens to prevent collision with the disk. Therefore, such an apparatus has a problem that the collision between the objective lens and the disk cannot be completely prevented.
[0005]
[Prior art]
As a conventional technique for preventing the collision between the objective lens and the disk, the distance between the optical head and the optical disk is widened while moving from one track to the next track. A technique for performing a load operation with a narrow interval is disclosed (see, for example, Patent Document 1).
[0006]
FIG. 13 is a diagram illustrating a configuration example of an optical information storage device. The prior art will be described with reference to FIG. First, when the disk 10 as a storage medium is set in the optical information storage device 20, the disk 10 is rotated at a predetermined rotational speed by a built-in spindle motor (not shown).
[0007]
Subsequently, a laser diode (not shown) emits light with a reading power, the photodetector 121 receives the reflected light of the light spot collected on the disk surface by the objective lens 131, and the output photocurrent is output as a focus error signal generation circuit. Voltage conversion and calculation processing are performed at 112, and a focus error signal FE necessary for focus servo is obtained.
[0008]
The MPU 101 issues a focus servo command (COM) to the servo control circuit 102. The servo control circuit 102 causes the focus control circuit 105 to swing the objective lens 131 in the direction perpendicular to the disk surface, detects a zero cross of the focus error signal FE, and closes the servo loop. As a result, the optical disc is focused on a guide groove formed in a spiral shape in the circumferential direction of the disk 10, and a track error signal TE necessary for track servo is obtained from the track error signal generation circuit 111.
[0009]
Subsequently, the MPU 101 issues a track servo command to the servo control circuit 102. The servo control circuit 102 instructs the track control circuit 106 to close the servo loop. As a result, the objective lens 131 is controlled so that the light spot follows the center of the recording track formed in a spiral shape on the disk 10, and information can be recorded or reproduced. In this state, the MPU 101 waits for a recording or reproduction request from the host computer 1 and waits.
[0010]
When receiving a recording or reproduction request from the host computer 1, the MPU 101 first issues a seek command to the servo control circuit 102. The servo control circuit 102 instructs the track control circuit 106 to perform seek control on the track on which desired information is recorded. After moving the objective lens 131 to a desired track, the MPU 101 records or reproduces information of a desired length, and waits for a recording or reproduction request from the host computer 1 again.
[0011]
FIG. 14 is a flowchart showing the operation of the conventional apparatus. First, the optical head is moved to the target track (S1). In this state, data is read from the optical disk (storage medium) or written to the optical disk. Then, it is checked whether reading or writing has been completed (S2). If completed, it is checked whether a read or write instruction has been issued from the host computer (S3). If a read or write instruction is issued, the process returns to step S1 to move to the target track. Such an operation is repeated.
[0012]
By the way, if the recording or reproduction request from the host computer 1 is not received for a long time, the MPU 101 stops the track servo and the focus servo, or further stops the laser diode emission and the spindle motor rotation. There is a method of entering a so-called sleep mode, waiting until a recording or reproduction request is received.
[0013]
This method has the effect of reducing power consumption or reducing aging of the device, which is the main purpose. However, as described above, the objective lens and the disk are very close to each other. In the case of an apparatus that operates in such a state, when there is no request for recording or reproduction, the object lens and the disk are separated from each other, thereby avoiding the danger of the two colliding due to an unexpected situation.
[0014]
[Patent Document 1]
JP 59-129947 (2nd page, Fig. 1)
[0015]
[Problems to be solved by the invention]
However, when the focus servo is stopped and a standby state is entered, when there is a recording or playback request from the host computer, it must start again with an operation of searching for the zero cross of the focus error signal, and it takes time to return to the operation. As a result, the performance of the apparatus is reduced.
[0016]
Therefore, the time-out time until the focus servo is stopped after entering the sleep mode is inevitably long, and the effect of reducing the risk of collision can hardly be obtained.
[0017]
The present invention has been made in view of such a problem, and can prevent a disc (storage medium) and an objective lens from colliding with each other. The focus control device for an optical information storage device is excellent in high-speed response. The purpose is to provide.
[0018]
[Means for Solving the Problems]
(1) The invention described in claim 1 is as follows. FIG. 1 is a principle configuration diagram of the present invention. The same components as those in FIG. 13 are denoted by the same reference numerals. The apparatus shown in the figure constitutes a focus control device of an optical information storage device that collects a light beam on a storage medium with an objective lens and reads reproduction information and servo information from the reflected light.
[0019]
In the figure, 10 is a storage medium such as a disk, 131 is an objective lens for condensing a light beam on the storage medium, 132 is a focusing operation for focusing the objective lens 131 on the surface of the storage medium 10 and the track is a target position. Reference numeral 121 denotes an actuator that performs an operation for adjusting the light intensity of the reflected light from the storage medium 10 into an electric signal. The objective lens 131, the actuator 132, and the photodetector 121 constitute a so-called optical head. In some cases, the photodetector 121 is placed outside and a combination of the objective lens 131 and the actuator 132 is used as an optical head.
[0020]
Reference numeral 30 denotes a focus control means for driving the actuator 132 to stably follow the reflective position of the storage medium 10, and reference numeral 21 denotes a target value for the deviation of the objective lens 131 from the focus position with respect to the storage medium 10. The focus target position signal generating means for giving the output to the focus control means 30. The actuator 132 moves the objective lens 131 in a direction perpendicular to the surface of the storage medium 10 in accordance with the output of the focus control means 30 to position the focal position.
[0021]
Reference numeral 1 denotes a host computer (host) that makes a recording or reproduction request. Reference numeral 101 denotes an output of a focus target position signal in a direction away from the storage medium 10 when a recording or reproduction request is not obtained from the host computer 1. When the recording or reproducing operation is being performed, the control unit instructs the focus target position signal generating unit 21 to output a focus target position signal that focuses on the recording surface of the storage medium 10.
[0022]
According to this configuration, when the recording or reproduction request from the host computer 1 cannot be obtained, the control means 101 outputs the output of the focus target position signal in the direction away from the storage medium 10 to the recording or reproduction. When the operation is being performed, the focus target position signal generation means 21 is instructed to output the focus target position signal so that the recording surface of the storage medium 10 is focused. ) 10 and the objective lens 131 can be prevented from colliding with each other.
[0023]
  Further, according to the present invention, since the objective lens 131 is separated without stopping the focus servo, the operation can be promptly restored when a recording or reproduction request from the host computer 1 is received. Is excellent.In addition, when a recording or reproduction request from the host computer cannot be obtained, the target position of the focus servo is gently separated from the zero point by a specified displacement amount to prevent the occurrence of overshoot and the storage medium and the objective lens Can be prevented. Furthermore, in-focus control of the optical head can be facilitated.
[0028]
In the present invention, when the recording or reproduction request from the host computer cannot be obtained, the control means stores the focus error signal to the focus target position signal generating means for controlling the focus position of the objective lens. The objective lens is instructed to be localized on the side away from the medium.
[0029]
With this configuration, the objective lens can be localized at a predetermined position even when the focus error signal exceeds the dynamic range.
[0030]
In the present invention, when the recording or reproduction request from the host computer cannot be obtained, the control means is arranged on the side away from the storage medium of the focus error signal with respect to the focus target position signal generating means. And instructing the objective lens to be localized, and turning off the laser diode that irradiates the storage medium.
[0031]
If comprised in this way, the collision of a storage medium and an objective lens can be prevented, and the lifetime of a laser diode can be extended.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0033]
FIG. 2 is a block diagram showing a first embodiment of the present invention. 1 and 13 are denoted by the same reference numerals. In the figure, 10 is a disk as a storage medium, 131 is an objective lens that focuses the light beam on the surface of the disk 10, 132 is the objective lens 131 in the vertical direction (up and down direction in the figure) or the radial direction of the storage medium 10 An actuator 121 to be moved to a photo detector 121 converts a detection signal from the disk 10 into an electric signal.
[0034]
Reference numeral 30 denotes a focus control circuit as focus control means for driving the actuator 132 to stably follow the reflection position of the storage medium 10, and reference numeral 21 denotes a target value for a deviation from the focus position of the objective lens 131 with respect to the disk 10. This is a focus target position signal generation circuit as a focus target position signal generation means for supplying the output to the focus control circuit 30. 101, when a recording or reproduction request from the host computer 1 is not obtained, a focus target position signal output in a direction away from the disk (storage medium) 10 is being recorded or reproduced. The MPU is a control unit that instructs the focus target position signal generation circuit 21 to output a focus target position signal that focuses on the recording surface of the storage medium 10.
[0035]
The focus target position signal generation circuit 21 receives a servo control circuit 102 that performs servo control in response to a command from the MPU 101, receives an output FT of the servo control circuit 102, and a focus error signal FE from the focus error signal generation circuit 112. , And a differencer 103 that gives the difference between these two signals to the focus control circuit 30. Here, the focus error signal FE is calculated and output by the focus error signal generation circuit 112 based on the photocurrent from the photodetector 121.
[0036]
Reference numeral 111 denotes a track error signal generation circuit that receives the output of the photodetector 121 and generates a track error signal TE. Reference numeral 112 also denotes a focus error signal generation circuit that receives the output of the photodetector 121 and generates a focus error signal FE. A difference unit 104 receives the track error signal TE from the track error signal generation circuit 111 and compares it with zero (0). Reference numeral 106 denotes a track control circuit that receives the output of the differentiator 104 and performs track control. The track control circuit 106 drives the actuator 132 in the radial direction of the disk 10. The operation of the apparatus configured as described above will be described with reference to the flowchart shown in FIG.
[0037]
The control means 21 sends a control signal to the track control circuit 106 to move to the target track (S1). Then, reading or writing to the disk 10 is performed. Next, it is checked whether reading or writing has been completed (S2). The flow of operations from when the disk 10 is set in the optical information storage device 20 until when the MPU 101 waits for a recording or reproduction request from the host computer 1 is the same as that described for the prior art with reference to FIG. is there. When step S2 ends, the optical information storage device 20 enters a standby state.
[0038]
If no recording or reproduction request is received from the host computer 1 even in the standby state, the MPU 101 issues a track servo release command (COM) to the servo control circuit 102 (S4-1). At this time, the servo control circuit 102 instructs the track control circuit 106 to open the track servo loop.
[0039]
Subsequently, the MPU 101 issues a focus withdrawal command to the servo control circuit 102 (S4-2). At this time, the servo control circuit 102 changes the focus target position signal FT input to the addition terminal of the differentiator 103 from 0 to VF. As a result, the objective lens 131 is moved to a position separated by PF from the focal position.
[0040]
This operation will be described in detail with reference to FIG. FIG. 4 is an explanatory diagram of the focus error signal. (A) shows the characteristics of the focus error signal FE, and (b) shows the relationship between the objective lens and the disc. In (a), the vertical axis represents the focus error signal FE, and the horizontal axis represents the defocus position (focus error) X. This position X is the distance from the position where the objective lens 131 is focused as shown in (b) to the reflecting surface of the disk 10.
[0041]
As shown in FIG. 4, the focus error signal is generally shaped to cross the zero level at the focal position. The leftward direction on the horizontal axis corresponds to the direction in which the objective lens 131 is separated from the disk 10. When the focus target position signal FT is at the zero level, the focus error signal FE is fed back with the zero point as a target, and at this time, the objective lens 131 is controlled to focus on the reflecting surface of the disk 10. Specifically, when the focus control circuit 30 drives the actuator 132, the objective lens is controlled to move in a direction perpendicular to the disk 10.
[0042]
Here, when the focus target position signal FT is set so that FT = VF, the focus error signal FE is fed back with VF as a target. As a result, the objective lens 131 is controlled so that the distance between the focal point and the reflecting surface of the disk 10 is maintained at PF. The distance PF is the distance of defocus X corresponding to the focus target position signal VF. In this state, the MPU 101 waits until there is a recording or reproduction request from the host computer 1 (S3).
[0043]
When the MPU 101 receives a recording or reproduction request from the host computer 1, the MPU 101 issues a focus entry command to the servo control circuit 102 (S5-1). At this time, the servo control circuit 102 changes the focus target position signal FT input to the addition terminal of the differentiator 103 from VF to 0. As a result, the objective lens 131 instantaneously moves from the separation distance PF to the focal position. In the present invention, since the focus servo is separated by the distance PF without stopping, when a recording or reproduction request from the host computer 1 is received, the operation can be quickly restored.
[0044]
Subsequently, the MPU 101 issues a track servo command to the servo control circuit 102 (S5-2). At this time, the servo control circuit 102 instructs the track control circuit 106 to close the track servo loop.
[0045]
Subsequently, the MPU 101 issues a seek command to the servo control circuit 102. The servo control circuit 102 instructs the track control circuit 106 to perform seek control on a track on which desired information is recorded. After the track control circuit 106 drives the actuator 132 and moves the objective lens 131 to a desired track, the MPU 101 records or reproduces information of a desired length.
[0046]
Thus, according to this embodiment, the control means 21 outputs the focus target position signal in the direction away from the disk 10 when the recording or reproduction request from the host computer 1 cannot be obtained. When a recording or reproducing operation is being performed, the focus control circuit 30 is instructed to output a focus target position signal for focusing on the recording surface of the disk 10, so that a storage medium (disk ) 10 and the objective lens 131 can be prevented from colliding with each other.
[0047]
FIG. 5 is a block diagram showing a second embodiment of the present invention. The same components as those in FIG. 2 are denoted by the same reference numerals. In the embodiment shown in the figure, a first focus error signal and a second focus error signal are generated as focus error signals. In the figure, reference numeral 112 denotes a focus error signal generation circuit similar to that shown in FIG. 2, which generates a first focus error signal here. A second focus error signal generation circuit 125 receives the output of the photo detector 121 and generates a second focus error signal.
[0048]
The focus error signal output from the first focus error signal generation circuit 112 is FE1, and the focus error signal output from the second focus error signal generation circuit 125 is FE2. A switch 122 receives the first and second focus error signals FE1 and FE2 and selects one of them. The switch 122 is switched by a control signal from the servo control circuit 102. Other configurations are the same as those in FIG. The operation of the apparatus configured as described above will be described as follows.
[0049]
In this embodiment, the second focus error signal having a wide dynamic range is used so that the gap (separation distance) when the focus is retracted can be maintained in a wider range.
[0050]
When a recording or reproduction request from the host computer 1 cannot be obtained, the MPU 101 issues a focus withdrawal command to the servo control circuit 102. The servo control circuit 102 that has received this focus evacuation command sends a selection signal to the switch 122 so as to select the second focus error signal FE2. As a result, the second focus error signal FE2 is given to the differentiator 103.
[0051]
On the other hand, the servo control circuit 102 sets the focus target position signal FT given to the addition terminal of the differentiator 103 to VF. As a result, the feedback loop shown in the figure performs feedback control such that FT = FE2, and the defocus is kept at PF.
[0052]
FIG. 6 is an explanatory diagram of the focus error signal. The vertical axis represents the focus error signal FE, and the horizontal axis represents the defocus X. The definition of defocus X is the distance from the focal position to the surface of the disk 10 as described with reference to FIG. FE1 is a first focus error signal, and FE2 is a second focus error signal. The first focus error signal FE1 is used during recording or reproduction on the disk 10, and the second focus error signal FE2 is used during retraction.
[0053]
The first focus error signal FE1 having a narrow dynamic range is used during recording or reproduction on the disk 10. As is clear from the figure, the dynamic range in the defocus X direction is narrow, but the focus position can be set close to the surface of the disk 10 with high accuracy. On the other hand, the second focus error signal FE2 having a wide dynamic range is used during retraction. Although the positioning with high accuracy cannot be performed as compared with the first focus error signal FE1, the position between the separations can be set wide, so that the distance between the surface of the disk 10 and the objective lens 131 can be widened and widened. The focus servo can be operated without stopping at the position.
[0054]
Here, when the MPU 101 receives a recording or reproduction request from the host computer 1, the MPU 101 issues a focus entry command to the servo control circuit 102. Upon receiving this command, the servo control circuit 102 sends a selection signal to the switch 122 so as to select the first focus error signal FE1. As a result, the first focus error signal FE1 is given to the differentiator 103 as a result.
[0055]
On the other hand, the servo control circuit 102 sets the focus target position signal FT to be given to the addition terminal of the differentiator 103 to zero. As a result, the feedback loop shown in the figure performs feedback control such that FT = FE1, and the defocus is kept at zero. That is, the surface of the disk 10 is focused. The focus error signal characteristic is FE1 in FIG. 6, and high-precision focus position control can be performed.
[0056]
Here, the second focus error signal FE2 may be generated from a separately provided photo detector instead of the photo detector 121, or may be a method of directly measuring the displacement of the objective lens 131 using a position sensor. The servo control circuit 102 sets the switch 122 so that the output FE1 from the first focus error signal generation circuit 112 is selected during recording or reproduction, and the output FE2 from the second focus error signal generation circuit 125 is selected during retraction. Switch. As a result, it is possible to perform control such that the gap (separation distance) when the focus is retracted is maintained in a wide range.
[0057]
FIG. 7 is a flowchart showing an example of the second operation of the present invention. As an apparatus configuration diagram, FIG. 2 is used. First, a normal operation is performed to move to the target track (S1), and a read or write operation is performed. Then, it is checked whether reading or writing to the disk 10 is completed (S2). When reading or writing is completed, the track servo is not released immediately, and a recording or reproduction request is waited for a predetermined time T1 (S6-1). At that time, the MPU 101 checks whether a read or write instruction has been issued before the predetermined time T1 elapses (S6-2). If an instruction is issued, the process returns to step S1, moves to the target track, and performs a read or write operation.
[0058]
If the time T1 has elapsed in step S6-1, the track servo is released (S4-1), and then the focus is retracted (S4-), as in the embodiment shown in FIG. 2). The subsequent flow is the same as that shown in FIG. That is, it is checked whether a read or write instruction has been issued in the evacuated state (S3). If an instruction is issued, focus entry is performed (S5-1), and track servo is started (S5-2).
[0059]
According to this embodiment, it is possible to prevent frequent focus evacuation by providing a time-out period for request monitoring from the host 1.
[0060]
Further, in the focus retract control (S4-2) or the focus entry control (S5-1), the focus target position signal FT output from the servo control circuit 102 is not a step change but gradually a target over a certain time. A target variation that changes the position may be output.
[0061]
FIG. 8 is an operation time chart of the present invention. (A) shows issuance of a focus retract command (S4-2) and focus entry command (S5-1), (b) shows a focus target position signal FT, and (c) shows a focus error signal FE. . When the focus command is issued and the focus target position signal FT is changed stepwise as shown in (b), the focus error signal FE is likely to cause overshoot as shown in (c). For this reason, there is a risk of deviating from the dynamic range of the focus error signal.
[0062]
On the other hand, as shown in FIG. 9, for example, in the case of a system having a target trajectory in which the focus target position signal FT changes gently in a ramp shape as shown in FIG. The error signal FE has an advantage that it follows smoothly as shown in FIG.
[0063]
FIG. 10 is a flowchart showing an example of the third operation of the present invention. FIG. 2 is used as an apparatus configuration diagram. First, the target track is moved (S1), and reading or writing is performed on the disk 10. Then, the MPU 101 checks whether reading or writing has been completed (S2). When reading or writing is completed, the track servo is released (S4-1).
[0064]
Next, focus retraction control is started (S4-2-1). Next, it is checked whether or not the saving control is completed (S4-2-2). When the saving control is completed, it is checked whether a read or write instruction is issued (S3). When a read or write instruction is issued, focus entry control is performed (S5-1), and track servo is started (S5-2). When the track servo is started, the process returns to step S1 to start the read or write operation.
[0065]
In step S4-2-2, it is checked whether a read or write instruction has been issued in a state where the evacuation control is not completed (S4-2-3). If an instruction is issued, the focus target position signal FT is immediately returned to 0 without waiting for completion of the focus retraction control, and the focus entry control is completed.
[0066]
FIG. 11 is an operation time chart of the present invention at this time. (A) shows an issue command, (b) shows a focus target position signal FT, and (c) shows a focus error signal FE. First, as shown in (a), when a focus withdrawal command signal is issued (S4-2-1), the servo control circuit 102 sets the slope-like focus target position signal FT to (b) in order to perform withdrawal control. Output as shown.
[0067]
Here, it is assumed that before the retracting operation of the optical head unit is completed, a recording or reproducing request is generated during the retracting and a focus entry command is issued as shown in FIG. When the servo control circuit 102 receives this focus entry command, it immediately raises the focus target position signal FT to 0 in the form of a slope before the slope falling is completed as shown in FIG. As a result, the focus error signal promptly enters the focus entry control without causing an overshoot as shown in (c).
[0068]
According to this embodiment, when a request is received from the host 1 immediately after the start of evacuation, the focus on state can be quickly established.
[0069]
FIG. 12 is a flowchart showing an example of the fourth operation of the present invention. This embodiment is a combination of the operation shown in FIG. 7 and the operation shown in FIG. That is, step S20 is the operation shown in FIG. 7, and step S30 is the operation shown in FIG.
[0070]
As an apparatus configuration diagram, FIG. 2 is used. First, a normal operation is performed to move to the target track (S1), and a read or write operation is performed. Then, it is checked whether reading or writing to the disk 10 is completed (S2). When reading or writing is completed, the track servo is not released immediately, and a recording or reproduction request is waited for a predetermined time T1 (S6-1). At that time, the MPU 101 checks whether a read or write instruction has been issued before the predetermined time T1 elapses (S6-2). If an instruction is issued, the process returns to step S1, moves to the target track, and performs a read or write operation.
[0071]
In step S6-1, when the time T1 has elapsed, the track servo is released (S4-1). Next, focus retraction control is started (S4-2-1). Next, it is checked whether or not the saving control is completed (S4-2-2). When the saving control is completed, it is checked whether a read or write instruction is issued (S3). When a read or write instruction is issued, focus entry control is performed (S5-1), and track servo is started (S5-2). When the track servo is started, the process returns to step S1 to start the read or write operation.
[0072]
In step S4-2-2, when a reading or writing instruction is issued in a state where the retraction control is not completed, the focus target position signal FT is immediately returned to 0 without waiting for the completion of the focus retraction control. Perform entry control.
[0073]
According to this embodiment, in-focus control of the optical head can be easily performed, and occurrence of overshoot can be prevented.
[0074]
Further, in the above-described embodiment of the present invention, focus retraction control cannot be performed at a position exceeding the dynamic range of the focus error signal FE, for example, an area of X <PFm in FIG. In such a case, the actuator 132 that drives the objective lens 131 has a mechanism having a return to origin function, for example, a spring support mechanism, and instructs the focus control circuit 30 to apply a constant current to the actuator 132. , X <PFm, the objective lens 131 can be localized.
[0075]
However, since the focus loop is opened when the focus is retracted (S4-2: see FIG. 7), the focus error signal FE must be zero-crossed again during the focus entry (S5-1).
[0076]
According to this embodiment, the objective lens can be localized at a predetermined position even when the focus error signal exceeds the dynamic range.
[0077]
Further, when the retracting method with the focus servo loop opened as described above is used, the laser diode may be turned off when the focus is retracted. As a result, the life of the laser diode can be extended.
[0078]
As described above, according to the present invention, when there is no recording or reproduction request from the host computer, the target position of the focus servo is set in a direction away from the disk, and the objective lens is closed with the focus servo loop closed. Can be separated from the disk to prevent collision between the two. Furthermore, when a recording or reproduction request is received from the host computer, the target position of the focus servo is set to the focal position, so that recording or reproduction can be performed immediately compared to a method such as the conventional sleep mode. .
[0079]
(Supplementary note 1) A focus control device of an optical information storage device that collects a light beam on a storage medium with an objective lens and reads reproduction information and servo information from the reflected light,
An actuator for controlling the focal position of the objective lens according to a control signal;
Focus control means for driving the actuator to stably follow the reflecting surface of the storage medium with the focal position;
A focus target position signal generating means for giving a target value to a deviation from the focal position of the objective lens with respect to the storage medium and giving an output thereof to the focus control means;
When the recording or reproduction request from the host computer cannot be obtained, the output of the focus target position signal in the direction away from the storage medium is performed. When the recording or reproduction operation is performed, the storage medium Control means for instructing the focus target position signal generating means to output a focus target position signal for focusing on the recording surface;
A focus control device for an optical information storage device.
[0080]
(Additional remark 2) The 1st focus error detection means which detects the shift | offset | difference from the focus position of the said objective lens with respect to the said storage medium,
Second focus error detection means for detecting a deviation from the focal position of the objective lens with respect to the storage medium in a wider range than the first focus error signal;
A switch circuit for switching and outputting the first focus error signal and the second focus error signal;
Comprising
The control means instructs the switch circuit to select the second focus error signal when the recording or reproduction request from the host computer cannot be obtained, and the focus target position signal generation means Instructing to output a focus target position signal in a direction away from the storage medium, instructing to select the first focus error signal when performing a recording or reproducing operation, and The focus control device for an optical information storage device according to appendix 1, wherein the focus target position signal generation means is instructed to output a focus target position signal so as to focus on the recording surface of the storage medium. .
[0081]
(Additional remark 3) The said control means monitors the time when the recording or reproduction | regeneration request | requirement from a host computer is not obtained, and when the time exceeds a predetermined threshold value, it is said memory | storage with respect to the said focus target position signal generation means. The focus control device for an optical information storage device according to appendix 1, wherein the focus target position signal output in a direction away from the medium is instructed.
[0082]
(Supplementary Note 4) When a recording or reproduction request from the host computer cannot be obtained, the control means sends the focus target position signal generation means from zero to a specified displacement amount within a specified time. 3. The focus control device for an optical information storage device according to any one of appendix 1 or 2, wherein a focus target position signal output having a trajectory that changes in a direction away from the storage medium is instructed.
[0083]
(Supplementary Note 5) When the recording or reproduction request is obtained from the host computer within the instruction time for outputting the focus target position signal, the control means is currently instructing even within the instruction time. The focus control device for an optical information storage device according to appendix 4, wherein the focus target position signal output means is instructed to output the focus target position signal having a trajectory that changes from a displacement amount to zero. .
[0084]
(Additional remark 6) When the recording or reproduction | regeneration request | requirement from a host computer is not obtained, the said control means is the said memory | storage of the said focus error signal with respect to the focus target position signal generation means which controls the focus position of an objective lens. 3. The focus control device for an optical information storage device according to appendix 1 or 2, wherein the objective lens is instructed to be positioned on the side away from the medium.
[0085]
(Supplementary Note 7) When the recording or reproduction request from the host computer cannot be obtained, the control unit is configured to move the focus error signal away from the storage medium with respect to the focus target position signal generation unit. The focus control device for an optical information storage device according to appendix 6, wherein the objective lens is instructed to be localized and the laser diode that irradiates the storage medium is turned off.
[0086]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
(1) According to the first aspect of the present invention, when the recording or reproducing request from the host computer cannot be obtained, the control means records the output of the focus target position signal in the direction away from the storage medium. Alternatively, when a reproducing operation is being performed, the focus target position signal generating means is instructed to output a focus target position signal that focuses on the recording surface of the storage medium. Disk) and the objective lens can be prevented from colliding with each other.
[0087]
  Further, according to the present invention, since the objective lens is separated without stopping the focus servo, when a recording or reproduction request is received from the host computer,PromptlyTherefore, it is possible to return to the operation mode, and it has excellent high-speed response.In addition, according to the present invention, when a recording or reproduction request from the host computer cannot be obtained, the overshoot can be generated by gently separating the target position of the focus servo from the zero point by a specified displacement amount. It is possible to prevent collision between the storage medium and the objective lens. Furthermore, in-focus control of the optical head can be facilitated.
[0088]
As described above, according to the present invention, it is possible to provide a focus control device for an optical information storage device that can prevent a collision between a disk (storage medium) and an objective lens and is excellent in high-speed response.
[Brief description of the drawings]
FIG. 1 is a principle configuration diagram of the present invention.
FIG. 2 is a configuration diagram illustrating a first exemplary embodiment of the present invention.
FIG. 3 is a flowchart showing an example of a first operation of the present invention.
FIG. 4 is an explanatory diagram of a focus error signal.
FIG. 5 is a configuration diagram showing a second exemplary embodiment of the present invention.
FIG. 6 is an explanatory diagram of a focus error signal.
FIG. 7 is a flowchart showing an example of the second operation of the present invention.
FIG. 8 is an operation time chart of the present invention.
FIG. 9 is an operation time chart of the present invention.
FIG. 10 is a flowchart showing an example of the third operation of the present invention.
FIG. 11 is an operation time chart of the present invention.
FIG. 12 is a flowchart showing an example of the fourth operation of the present invention.
FIG. 13 is a diagram illustrating a configuration example of an optical information storage device.
FIG. 14 is a flowchart showing the operation of the conventional apparatus.
[Explanation of symbols]
1 Host computer
10 storage media
21 Control means
30 Focus target position signal generating means
101 MPU
121 Photodetector
131 Objective lens
132 Actuator

Claims (1)

A focus control device for an optical information storage device that collects a light beam on a storage medium with an objective lens and reads reproduction information and servo information from the reflected light,
An actuator for controlling the focal position of the objective lens according to a control signal;
Focus control means for driving the actuator to stably follow the reflecting surface of the storage medium with the focal position;
A focus target position signal generating means for giving a target value to a deviation from the focal position of the objective lens with respect to the storage medium and giving an output thereof to the focus control means;
When the recording or reproduction request from the host computer cannot be obtained, the output of the focus target position signal in the direction away from the storage medium is performed. When the recording or reproduction operation is performed, the storage medium Control means for instructing the focus target position signal generating means to output a focus target position signal for focusing on the recording surface;
Provided ,
When the recording or reproduction request from the host computer is not obtained within a predetermined time threshold, the control means defines the objective lens from zero within a specified time with respect to the focus target position signal generating means. A focus target position signal output having a trajectory that gently changes in a direction away from the storage medium by the amount of displacement of the recording medium, and recording or recording from the host computer within the instruction time of the focus target position signal output When a reproduction request is obtained, a focus target position signal output having a trajectory that changes from the displacement amount currently indicated by the objective lens to zero even within the indicated time is output to the focus target position. A focus control device for an optical information storage device, characterized by instructing a position signal generating means .

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